The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a magnetically coupled safety valve with satellite outer magnets.
Operation of a safety valve using magnetic coupling across a pressure isolation barrier has been described in U.S. Pat. No. 6,988,556. The entire disclosure of this prior patent is incorporated herein by this reference.
A magnetic coupling force generated between two sets of annular shaped magnets in the prior patent is dependent mainly on the volume of magnetic material and the separation between the annular magnets. Unfortunately, space is very restricted in a downhole environment, which particularly limits the available volume in a safety valve, and when high pressure differentials need to be resisted by the pressure isolation barrier, these factors cause the magnetic coupling force to be significantly reduced.
Therefore, it may be seen that improvements are needed in the art of magnetically coupled safety valves. It is among the objects of the present invention to provide such improvements.